JPWO2018173618A1 - Method for producing prepreg and method for producing fiber-reinforced composite material - Google Patents

Abstract

The present invention, in the production of prepreg, to maintain the alignment of the reinforcing fiber, good straightness, and to provide a technology that can be applied stably at any speed with any resin, and to improve the production efficiency, In the method of manufacturing a prepreg, in which a molten resin is discharged in a planar shape and the formed resin film 2 is applied onto a continuously conveyed reinforcing fiber sheet 1a, the reinforcing fiber sheet 1a is conveyed substantially horizontally. The essence of the present invention is to manufacture a prepreg at an angle of 80 ° or less between the resin discharge direction and the reinforcing fiber sheet 1a conveyance direction. [Selection diagram] Fig. 1

Description

  The present invention relates to a method for efficiently producing a prepreg which is a precursor of a fiber-reinforced composite material.

  Fiber reinforced composite material (FRP), which is a matrix resin containing thermoplastic resin and thermosetting resin reinforced with reinforcing fibers, is a material for aviation and space, automotive material, industrial material, pressure vessel, building material, housing, medical equipment. It is used in various fields such as applications and sports. Particularly when high mechanical properties and lightness are required, carbon fiber reinforced composite materials (CFRP) are widely and suitably used. On the other hand, when cost is prioritized over mechanical properties and light weight, a glass fiber reinforced composite material (GFRP) may be used. In the FRP, a reinforcing fiber is impregnated with a matrix resin to obtain an intermediate substrate, which is laminated and molded, and when a thermosetting resin is used, thermally cured to produce a member made of FRP. In the above-mentioned applications, there are many planar objects and those obtained by bending the same, and the two-dimensional sheet-like material is more often used as an intermediate substrate of FRP than a one-dimensional strand or roving-like material when producing a member. It is widely used from the viewpoint of lamination efficiency and moldability.

  Recently, in order to improve the production efficiency of members made of FRP, mechanization and automation of lamination of sheet-like intermediate base materials have been promoted, and narrow tape-like intermediate base materials are preferably used here. The narrow tape-shaped intermediate substrate can be obtained by slicing a wide sheet-shaped intermediate substrate at a desired width, or directly impregnating a narrow reinforcing fiber bundle sheet with a matrix resin.

  As a two-dimensional sheet-like intermediate base material, a prepreg in which a matrix resin is impregnated into a reinforcing fiber sheet in which reinforcing fibers are arranged and formed into a sheet is widely used. As the reinforcing fiber sheet used for the prepreg, there is a UD sheet in which reinforcing fibers are aligned in one direction and arranged in a sheet form, or a woven fabric arranged in multiple directions. In particular, when mechanical characteristics are prioritized, a UD sheet is often used. On the other hand, when shapeability is prioritized, a woven fabric may be used.

  In the hot melt method, one of the prepreg manufacturing methods, a matrix resin is melted and then coated on a release paper (resin film forming process), and a laminated structure is sandwiched between the upper and lower surfaces of the reinforcing fiber sheet. Then, the matrix resin is impregnated inside the reinforcing fiber sheet by heat and pressure. This method has a problem that the number of steps is large, the production speed cannot be increased, and the cost is high.

  In fields such as industrial applications where higher efficiency is required than the mechanical properties of FRP, a process of directly applying a resin to a reinforcing fiber sheet is being trialled in order to omit the resin film forming step. This is particularly often the case when a thermoplastic resin is used as the matrix resin. For example, Patent Literature 1 describes that a thermoplastic resin is directly applied to a reinforcing fiber sheet using a so-called T-die. Further, Comparative Example 1 of Patent Document 2 describes that PPS (polyphenylene sulfide), which is a thermoplastic resin, is laminated on a UD sheet using a film slit die (width: 100 mm).

  As Example 1 of Patent Document 3 describes that the production speed of prepreg is 5 m / min, there was a problem that the production speed of the conventional prepreg was low.

JP 2013-184356 A International Publication WO2003 / 091015 Pamphlet JP-A-2014-069391

From the viewpoint of the quality of the FRP, it is important to suppress fluffing or cutting of the reinforcing fibers due to abrasion or the like in the step of applying the matrix resin. In addition, in order to stabilize the mechanical properties and quality of FRP, it is important that the matrix resin to be applied has good uniformity in the basis weight (mass of matrix resin per 1 m ² ). Furthermore, especially when a UD sheet is used, the arrangement and straightness of the reinforcing fibers in the prepreg are important.

  Furthermore, in order to increase the efficiency, it is important to increase the conveying speed (line speed) of the reinforcing fiber sheet, which is the production speed of the prepreg, as high as possible.

  The method disclosed in Patent Document 1 in which a thermoplastic resin is discharged from a T-die and pressed against a reinforcing fiber sheet has problems that cutting and fuzzing of the reinforcing fibers, and disturbance in arrangement and straightness are likely to occur. . In addition, in this method, as shown in FIG. 3 of Patent Document 1, since a pool portion of the discharged resin is formed on the reinforcing fiber sheet, there has been a problem that the uniformity of the basis weight is easily deteriorated.

  When the method disclosed in Comparative Example 1 of Patent Document 2 is applied to a thermosetting resin, there has been a problem that the resin film is easily broken and uniform coating is difficult.

  That is, an object of the present invention is to provide a technique for maintaining a good arrangement of reinforcing fibers and straightness in the production of a prepreg, providing a technique for applying any resin stably at high speed, and improving production efficiency. It is.

  The above problem can be solved by the following manufacturing method. That is, the method for producing a prepreg according to the present invention is directed to a method for producing a prepreg in which a molten resin is discharged in a planar shape, and the formed resin film is applied onto a continuously conveyed reinforcing fiber sheet. Are transported in a substantially horizontal direction, and the angle between the resin discharge direction and the reinforcing fiber sheet transport direction is 80 ° or less.

  Further, the method for producing a fiber-reinforced composite material of the present invention is characterized in that after the prepreg is obtained by the above-described method for producing a prepreg, the prepreg is cured.

  ADVANTAGE OF THE INVENTION According to this invention, in manufacture of a prepreg, production efficiency can be improved by the technique which can maintain arrangement | positioning and straightness of a reinforcing fiber favorable, and can apply | coat any resin stably at high speed.

It is a schematic diagram showing an outline of an example of a manufacturing process of a prepreg according to the present invention. It is the side view to which the application part part in FIG. 1 was expanded. It is a side view of the application part in the conventional application method. It is the upper surface figure which looked at the application part neighborhood from the upper part. FIG. 4 is a front view for explaining a state of an end portion of the resin film (when airflow control is performed). FIG. 4 is a front view for explaining a state of an end portion of the resin film (without airflow control). FIG. 5 is a side view for explaining a state of a surface portion of the resin film (when airflow control is performed). FIG. 4 is a side view for explaining a state of a surface portion of the resin film (without airflow control). It is a side view which shows the example of the application part part provided with the control means by the airflow. It is a schematic diagram showing an outline of an example of a manufacturing process of a prepreg according to the present invention. It is a schematic diagram showing an outline by another example of a manufacturing process of a prepreg according to the present invention. It is a schematic diagram showing an outline by another example of a manufacturing process of a prepreg according to the present invention.

  A preferred embodiment of the present invention will be described with reference to the drawings. The following description is an example of one embodiment of the present invention, and the present invention is not limited to the embodiment, and various changes can be made without departing from the objects and effects of the present invention.

  First, the outline of the method for producing a prepreg of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing a method and an apparatus for applying a resin composition according to one embodiment of the present invention to a reinforcing fiber sheet.

  In the prepreg manufacturing apparatus 100, a plurality of creels 11 for unwinding the reinforcing fibers 1 and a reinforcing fiber sheet 1a in which the unwound reinforcing fibers 1 are arranged in one direction (the fibers are arranged in the depth direction of the paper in FIG. 1) are obtained. An arranging device 12, a transport roll 13 (13a, 13b, 13c) which is a traveling mechanism for traveling the reinforcing fiber sheet 1a substantially in the horizontal direction X, an application unit 20 from which the resin 2 is discharged in a plane, and a resin 2 is provided with a winding device 16 for the reinforcing fiber sheet 1b to which 2 is applied. Further, if necessary, a release sheet supply device 14 (14a, 14b) for supplying the release sheet 3 and a release sheet winding device 15 can be provided. Here, by making the traveling direction substantially horizontal, there is an advantage that an existing prepreg conveying device can be used. The term “substantially horizontal” means that the prepreg provided with the reinforcing fiber sheet 1a and the resin 2 is conveyed at an angle of 30 degrees from a horizontal plane in an area of 30 cm before and after the point where the resin 2 comes into contact with the reinforcing fiber sheet 1a. This means that the paper is being conveyed without any surface. From the viewpoint of utilizing the existing prepreg transport device, more specifically, it is preferable that the deviation of the transport direction from the horizontal plane is 15 ° or less.

  Here, as the reinforcing fiber 1, carbon fiber, graphite fiber, glass fiber, metal fiber, metal oxide fiber (such as alumina fiber), metal nitride fiber, silicon carbide fiber, boron fiber, tungsten carbide fiber, organic fiber ( Aramid fiber, polybenzoxazole fiber, polyvinyl alcohol fiber, polyethylene fiber, etc.), ceramic fiber and the like. As the reinforcing fiber, only one type of reinforcing fiber may be used for the same prepreg, or different types of reinforcing fiber may be used regularly or irregularly. It is preferable to use carbon fiber from the viewpoint of the mechanical properties and lightness of FRP.

  In addition, the reinforcing fiber sheet does not necessarily have to be integrated such that the reinforcing fibers are intertwined with each other, and FIG. 1 illustrates a UD sheet in which a plurality of reinforcing fibers are arranged in a plane in one direction. A woven fabric, a nonwoven fabric, a papermaking, and the like can be appropriately selected according to the use of the FRP. Here, the thickness and width of the reinforcing fiber sheet are not particularly limited, and can be appropriately selected depending on the purpose and application. In addition, it is preferable that the aspect ratio defined by the width / thickness of the reinforcing fiber sheet is 10 or more because it is easy to handle. FIG. 4 is a top view of the vicinity of the application portion in FIG. 1 as viewed from the direction B (above). The reinforcing fiber sheet 1a (in this case, a UD sheet) is drawn so as to be arranged with a gap between the reinforcing fibers 1, but in practice, it is necessary to arrange the reinforcing fibers 1 without any gaps in the quality of the prepreg. It is preferable from the viewpoint of the mechanical properties of FRP. Further, it is preferable to convey the reinforcing fiber sheet while applying an appropriate tension from the viewpoint of maintaining the arrangement of the reinforcing fibers.

  In addition, when a single fiber of the reinforcing fibers is formed into a tape shape by arranging the fibers, even if this is one thread, it corresponds to one form of the reinforcing fiber sheet.

  The resin application step can be performed, for example, by the following procedure. First, the resin is melted, weighed and transferred. In most prepregs, the resin is heated at room temperature because it is solid at room temperature. Further, when the resin is a viscous liquid at normal temperature, it can be used by reducing the viscosity to such an extent that the resin can be discharged from the discharge portion by heating, and in the present invention, such a case is also included in the melting. . For example, when a gear pump is used, the molten resin can be transferred to the application head while measuring the amount of the resin. Thereafter, the resin is divided into a plurality of flows in the application head and is guided to the discharge section, so that the distribution of the resin in the application head can be improved. Thereafter, the resin is guided to the discharge unit, and discharged from the discharge unit.

  Examples of the resin used in the present invention include a thermosetting resin, a thermoplastic resin, and a mixture of a thermosetting resin and a thermoplastic resin.

  Examples of the thermosetting resin include an epoxy resin, a maleimide resin, a polyimide resin, a resin having an acetylene terminal, a resin having a vinyl terminal, a resin having an allyl terminal, a resin having a nadic acid terminal, and a resin having a cyanate ester terminal. Can be These can be generally used in combination with a curing agent or a curing catalyst. In addition, these thermosetting resins can be appropriately used in combination.

  As a thermosetting resin suitable for the present invention, an epoxy resin is preferably used because of its excellent heat resistance, chemical resistance, and mechanical properties. In particular, an epoxy resin using an amine, a phenol, or a compound having a carbon-carbon double bond as a precursor is preferable. Specifically, various isomers of phenols such as tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, and triglycidylaminofresole as epoxy resins using amines as precursors. Bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, a compound having a carbon-carbon double bond as a precursor epoxy resin Examples of the epoxy resin include alicyclic epoxy resins, but are not limited thereto. Further, brominated epoxy resins obtained by brominating these epoxy resins are also used. An epoxy resin having an aromatic amine represented by tetraglycidyldiaminodiphenylmethane as a precursor has a good heat resistance and a good adhesion to a reinforcing fiber, and is most suitable for the present invention.

  A thermosetting resin is preferably used in combination with a curing agent. For example, in the case of an epoxy resin, a curing agent that is a compound having an active group capable of reacting with an epoxy group can be used. Preferably, a compound having an amino group, an acid anhydride group, or an azide group is suitable. Specifically, dicyandiamide, various isomers of diaminodiphenylsulfone, and aminobenzoic acid esters are suitable. More specifically, dicyandiamide is preferably used because of its excellent prepreg preservability. Further, various isomers of diaminodiphenyl sulfone are most suitable for the present invention because they give cured products having good heat resistance. As the aminobenzoic acid esters, trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate are preferably used. Compared with diaminodiphenyl sulfone, the heat resistance is lower, but the tensile strength is lower. Because it is excellent, it is selected and used according to the application. It is also possible to use a curing catalyst if necessary. From the viewpoint of improving the pot life of the thermosetting resin, it is also possible to use a complexing agent capable of forming a complex with a curing agent or a curing catalyst. These curing agents, curing catalysts, complexing agents and the like can be contained in the resin.

  The thermoplastic resin suitable for the present invention has a carbon-carbon bond, amide bond, imide bond, ester bond, ether bond, carbonate bond, urethane bond, urea bond, thioether bond, sulfone bond, imidazole bond, carbonyl A thermoplastic resin having a bond selected from bonds, more preferably polyacrylate, polyamide, aramid, polyester, polycarbonate, polyphenylene sulfide (PPS), polybenzimidazole (PBI), polyimide (PI), polyetherimide (PEI), polysulfone (PSU), polyethersulfone (PES), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyaryletherketone (PAEK), polyamideimide (PAI) UNA is a group of thermoplastic resins belonging to the engineering training plastic. In particular, PPS, PES, PI, PEI, PSU, PEEK, PEKK, PEAK, and PAI are suitable for the present invention because they have excellent heat resistance. The molecular weight of these thermoplastic resins is not particularly limited, and can be appropriately selected from oligomers to ultrahigh molecular weight substances. As the oligomer, an oligomer having a functional group capable of reacting with the thermosetting resin at the terminal or in the molecular chain can also be used.

  In the present invention, it is also preferable to use a thermoplastic resin mixed with the above-mentioned thermosetting resin. A mixture of a thermosetting resin and a thermoplastic resin gives better results than using the thermosetting resin alone. This is because the thermosetting resin is generally capable of low pressure molding by an autoclave while having a brittle defect, whereas the thermoplastic resin is generally difficult to perform low pressure molding by an autoclave while having the advantage of being tough. This is because they have different properties, and the properties can be balanced with the moldability by mixing and using them. When mixed and used, it is preferable to contain the thermosetting resin in an amount of more than 50% by mass of the total amount of the resin from the viewpoint of the mechanical properties of the FRP obtained by curing the prepreg.

  Further, in the present invention, the above-mentioned resin may preferably contain various additives according to the purpose of improving the characteristics of FRP, process stability, and the like. Examples of such additives include organic particles, inorganic particles, fillers, and function improvers, and more specific examples thereof include an organic polymer for improving toughness and vibration damping properties when FRP is used. Examples include carbon particles and carbon nanotubes for improving particles and conductivity. Further, organic materials and polymers for controlling the surface tackiness of the prepreg may be used.

  The organic polymer particles are preferably insoluble in the matrix resin. As such organic polymer particles, for example, those described in WO2009 / 142231 can be used. More specifically, polyamide or polyimide can be preferably used. Above all, polyamide, which can greatly improve impact resistance due to excellent toughness, is most preferable. As the polyamide, a semi-IPN (polymer interpenetrating network structure) using nylon 12, nylon 11, nylon 6, nylon 66 or a nylon 6/12 copolymer, or an epoxy compound described in Example 1 of JP-A-01-104624. Nylon (semi-IPN nylon) or the like can be suitably used. The shape of the thermoplastic resin particles may be a spherical particle, a non-spherical particle, or a porous particle, but a spherical shape is particularly preferable in the production method of the present invention since the flow characteristics of the resin are not deteriorated. Further, a spherical shape is a preferable embodiment in that there is no starting point of stress concentration and high impact resistance is given.

  Commercially available polyamide particles include SP-500, SP-10, TR-1, TR-2, 842P-48, 842P-80 (all manufactured by Toray Industries, Inc.) and "Orgasol (registered trademark)" 1002D. , 2001UD, 2001EXD, 2002D, 3202D, 3501D, 3502D (all manufactured by Arkema Co., Ltd.), "Grillamide (registered trademark)" TR90 (manufactured by Mazaverke Co., Ltd.), "TROGAMID (registered trademark)" CX7323, CX9701 , CX9704 (manufactured by Degussa Co., Ltd.) and the like can be used. These polyamide particles may be used alone or in combination of two or more.

  The present invention eliminates the step of forming a resin film by directly applying the resin to the reinforcing fiber sheet as compared with the method of forming the resin into a film in advance and manufacturing the resin in comparison with the hot melt method which is a conventional prepreg manufacturing method. The process can be made more efficient. Here, the method of applying the resin is important, and in the present invention, it is important to discharge the molten resin in a planar shape and apply the formed resin film onto a continuously conveyed reinforcing fiber sheet. is there. Here, forming a resin film by discharging in a plane means forming a film in a space where the resin is discharged, and the resin film is in a semi-solid state or a solid state even in a molten state. May be. For this reason, in the present invention, since non-contact application is performed, various types of abrasion between the application head and / or the discharge resin and the reinforcing fiber sheet are compared with those in which the application head is pressed against the reinforcing fiber sheet as described in Patent Document 1. Can solve the problem.

  Next, in the present invention, the reinforcing fiber sheet is transported in a substantially horizontal direction, and the angle formed between the resin discharge direction and the reinforcing fiber sheet transport direction (this angle may be referred to as “application angle” for convenience). It is important that the angle is not more than 80 °. FIG. 3 shows a conventional general coating method. The angle between the resin discharge direction and the reinforcing fiber sheet transport direction is 90 °. The present inventors conducted an experiment using a thermosetting resin (such as an epoxy resin). As a result, when the angle between the resin discharge direction and the reinforcing fiber sheet conveyance direction was 90 °, the coating could be performed stably. Did not. When the application head is pressed as described in Patent Document 1, such a problem is not considered to occur because no resin film is formed in the air. However, by setting the angle between the resin discharge direction and the reinforcing fiber sheet conveyance direction shown in FIG. 1 to be equal to or less than 80 °, even when the resin is discharged in a planar shape to form a resin film, the resin film can be stably formed. The present inventors have found that coating can be performed at high speed. The smaller the coating angle θ is, the more stable the coating can be performed at a high speed. However, when the coating angle θ is small, the size of the coating head easily interferes with the process of transporting the reinforcing fiber sheet, and thus there may be a case where restrictions are imposed on the apparatus. From this viewpoint, the coating angle θ is preferably set to 30 to 70 °.

  By setting the application height H, which is the distance between the center of the ejection line and the reinforcing fiber sheet 1a, shown in FIG. 2 to 3 mm or more, it is possible to suppress the contamination of the application portion due to the accumulation of resin in the application portion and to improve the application stability. It is preferable because it can be improved. Further, it is preferable that the thickness be 18 mm or less because the formation of the resin film in the space where the resin is discharged is stabilized.

  The coating unit 20 may be any device that can discharge the resin in a planar manner. More specifically, a preferred example is an apparatus capable of forming a surface or curtain-like film by discharging a resin having a uniform thickness in a width direction from a die for discharging the resin. Generally, it is a planar coating device called a curtain coating device or a die coater, and can use a structure that can discharge resin from a slit having a uniform thickness and no intermittent slits. Further, it is preferable that the application unit 20 has a heating mechanism that heats the resin 2 immediately before the discharge and can adjust the viscosity to an arbitrary viscosity. Especially when using a thermosetting resin, there is a risk of deterioration due to heat history of the resin during storage, increase in viscosity, and runaway reaction, so it is necessary to shorten the heating time of the resin and perform appropriate temperature control. preferable.

  Further, in the present invention, since the resin film has a free surface in the space where the resin is discharged, the film shape of the resin film is easily deformed. For example, the resin film is not formed due to the so-called “neck-in” in which the end of the resin film is shrunk in the width direction, or the entire resin film is pulled when the reinforcing fiber sheet is conveyed at a high speed. In some cases, the resin film becomes stable or the uniformity of the basis weight of the resin film is impaired. For this reason, it is preferable to apply an air current to the widthwise end of the resin film to stabilize the film formation.

  In the resin film, a phenomenon called “neck-in” occurs in which the edge of the resin film is drawn in the center direction of the resin film in a direction perpendicular to the pulling direction and the width of the resin film is reduced (see FIGS. 5 and 6). The width is reduced by the amount indicated by G). This phenomenon is likely to occur particularly when a high tension is applied to the resin film due to a high viscosity of the resin or a high pulling speed. In particular, when forming a resin film at a high speed by the prepreg manufacturing method of the present invention, it is preferable to suppress neck-in. For this reason, in the present invention, it is preferable that the air flow is applied from the front surface of the resin film toward the end portion, and the air flow is applied so as to expand the end portion of the resin film by, for example, spraying (FIG. 4). The airflow for this is called end air in the present invention. Generally, a metal pipe or a nozzle can be used as a means for applying the end air. It is preferable that the airflow velocity, flow rate, angle, position, and temperature of the end air be appropriately selected in consideration of, for example, whether neck-in or resin film formation is stably performed. The end air can be used when applying the resin film. When applying, the resin film is formed before the resin is started to be discharged from the die, when the resin is started to be discharged from the die, when the resin is discharged from the die, and when the resin film is coated on the reinforcing fiber sheet. The method can be appropriately selected and applied.

  Further, as shown in FIG. 8, the resin film may be excessively pulled in the pulling direction of the resin film, that is, in the prepreg conveying direction. In this case, for example, as shown in FIG. Alternatively, it is preferable that an airflow is blown toward almost the entire surface to bring the position where the resin film comes into contact with the reinforcing fiber sheet closer to the application portion side. In the present invention, the airflow for this purpose is called surface air. It is preferable that the airflow velocity, flow rate, angle, position, and temperature of the surface air be appropriately selected in consideration of whether or not the resin film is formed stably. As a means for applying the surface air, a nozzle in which slits or holes are arranged in a line can be generally used. In addition, it is preferable that both the end air and the surface air are provided with the application device in the application section, from the viewpoint of making the device compact and handling. Regarding the action on the surface of the resin film, the position where the resin film comes into contact with the reinforcing fiber sheet can be made closer to the application portion side by sucking air from the back side of the resin film.

  The release sheet used in the present invention is not particularly limited as long as it has a sufficient release property with respect to a resin to be applied and has appropriate elasticity and rigidity, for example, a film coated with release paper or a release agent. Etc. can be used.

  In the present invention, the transport speed (line speed) of the reinforcing fiber sheet or prepreg is preferably higher from the viewpoint of improving productivity. However, on the other hand, attention must be paid to the fact that as the transport speed increases, equipment investment for stable transport may be required. In this sense, the transport speed is preferably from 10 m / min to 100 m / min.

  In the present invention, an impregnation step can be incorporated after the resin application step as shown in FIG. 1 if necessary. That is, the impregnation operation can be performed after the resin is applied on the continuously conveyed reinforcing fiber sheet. By impregnating, the resin applied on the reinforced fiber sheet penetrates into the reinforced fiber sheet, which improves the handling properties as a prepreg and causes unimpregnated parts even when processed into a composite material. Can effectively be suppressed from occurring, and a decrease in mechanical properties can be suppressed. In the case of a prepreg having many unimpregnated portions, the convergence of the reinforcing fibers is insufficient, so that the handleability may be deteriorated. Therefore, not only the mechanical properties but also the grade may be deteriorated.

  The impregnating device is not particularly limited, and can be appropriately selected from known devices according to the purpose. For example, as described in JP-A-2011-132389 and WO2015 / 060299, a laminate of a reinforcing fiber sheet and a resin is preheated with a hot plate to sufficiently soften the resin on the reinforcing fiber sheet, Impregnation can be promoted by using a device that presses with a heated nip roll. The temperature of the hot plate for preheating, the surface temperature of the nip roll, the linear pressure of the nip roll, and the diameter and number of the nip rolls can be appropriately selected so as to obtain a desired impregnation degree. It is also possible to use an “S-wrap roll” in which a prepreg sheet travels in an S-shape as described in WO 2010/150022 pamphlet. FIG. 1 of WO 2010/150022 pamphlet describes an example in which the prepreg sheet travels in an S-shape, but if impregnation is possible, the contact between the sheet and the roll, such as a U-shape, V-shape, or Λ-shape, is described. The length may be adjusted. When the impregnation pressure is increased to increase the degree of impregnation, it is also possible to add an opposing contact roll. Furthermore, as shown in FIG. 4 of WO2015 / 076981, it is possible to improve the impregnation efficiency by arranging the conveyor belt opposite to the “S-wrap roll” and to increase the production speed of the prepreg. Further, as described in WO 2017/068159 pamphlet or JP-A-2006-20397, etc., it is possible to improve the impregnation efficiency by applying ultrasonic waves to the prepreg before the impregnation and rapidly raising the temperature of the prepreg. is there. Further, as described in JP-A-2017-154330, it is also possible to use an impregnation device that vibrates a plurality of “ironing blades” with an ultrasonic generator. Further, it is also possible to fold and impregnate the prepreg as described in JP-A-2013-22868.

  In the present invention, both a resin laminated on a reinforcing fiber sheet and a resin fully impregnated with a reinforcing fiber are referred to as a prepreg.

  Although FIG. 1 shows only one coating unit and one impregnation machine, it is of course possible to connect and install a plurality of these units. For example, when two application units and two impregnation machines are used, a so-called two-stage impregnation in which a second resin composition containing a large amount of resin particles is applied and impregnated can be performed. In addition, by applying a highly reactive component and a stable component separately by using a plurality of coating heads, it is possible to apply a highly reactive component in a low reactivity state (for example, at a low temperature). . It is also possible to apply components having a high melt viscosity separately (for example, at a high temperature and / or at a large ejection area). It is preferable to use a plurality of coating heads, since the coating conditions that can be obtained in the coating process can be made flexible.

  When two or more application heads are used, the resin can be applied to both sides of the reinforcing fiber sheet. It is of course possible to apply the resin to only one side and impregnate the resin from one side. However, by applying the resin to both sides and impregnating the resin from both sides, the quality of the prepreg can be increased and the generation of voids can be suppressed. For the application of resin on both sides, multiple coating heads may be placed on the front and back at the same position, and both sides may be coated at the same time, or resin may be applied to one side and then applied to the other side. May be performed.

  FIG. 10 shows an example of a coating method on both sides. A plurality of reinforcing fibers 1 are pulled out from the creel 11 and a reinforcing fiber sheet 1 a is formed by the arrangement device 12. Thereafter, the release sheet 3a fed from the release sheet supply device 14a is inserted into the lower surface of the reinforcing fiber sheet 1a by the transport roll 13a. Thereafter, the resin 2a is discharged from the first coating head 20a, and the prepreg 1b to which the resin 2a is applied is formed. Then, the upper surface and the lower surface of the prepreg are reversed via the transport rolls 13b and 13c. In addition, the release sheet 3a is peeled off by the transport roll 13c, and instead, the release sheet 3b is inserted into a surface of the prepreg 1b on which the resin 2a is applied, which is opposite to the surface on which the resin 2a is applied. Then, the resin 2b is discharged from the second application head 20b, and the prepreg 1c to which the resin is applied is formed from both sides of the reinforcing fiber sheet. Further, the release sheet 3c is superimposed on the prepreg 1c by the transport roll 13d, and is impregnated using the impregnating machine 17. Thereafter, the release sheet 3c can be peeled off by the transport roll 13e via the cooling device 19, and can be wound up by the winding device 16. In FIG. 10, the means for applying the end air and the surface air are not shown. The resin 2a, the resin 2b, and the resin 2c may be the same type of resin or different types of resins, and may each contain additives or particles.

  FIG. 11 shows another example of the application method on both surfaces. This example is different from the example in FIG. 10 in that the reinforcing fiber sheet provided with the resin is conveyed in the horizontal direction without being folded. Again, the means for applying the end air and the surface air are not shown. The application of the resin from the application head 20b can be performed using non-contact physical means such as wind power or electrostatic means.

  When a plurality of application heads are used, different resins can be laminated from each application head, or a curing agent or various additives can be applied. This will be described in detail with reference to FIG. Although FIG. 12 illustrates a case where the number of application heads is three, the number of application heads may be two or four or more. In addition, the case where the number of impregnating machines is two is illustrated, but one impregnating machine or three or more impregnating machines may be used, and the installation location may be appropriately changed according to the purpose.

  First, the resin 2a is applied to the reinforcing fiber sheet 1a by the first application head 20a, and a prepreg 1b to which the resin 2a is applied is formed. Then, the prepreg 1d to which the resin 2b is applied is formed by the second coating head 20b. Further, the resin 2c is applied from the third application head 20c. Further, the impregnating machine 17 may be provided after the first coating head 20a, after the second coating head 20b, or after the third coating head 20c. Further, as illustrated in FIG. 12, the first impregnating machine 17a may be arranged after the second coating head 20b, and the second impregnating machine 17b may be arranged after the third coating head 20c.

  In the present invention, in applying a resin onto a reinforcing fiber sheet conveyed in a substantially horizontal direction, the resin is discharged in a planar shape, and the angle between the resin discharging direction and the reinforcing fiber sheet conveying direction is 80 °. It has a step of applying a resin as follows, but if the above-described step is included, as long as the object of the present invention is not impaired, a resin application step not based on this step is used in combination. No problem. For example, there is a mode in which a thermosetting resin is discharged from the first coating head, and a curing agent is discharged from the second coating head. Further, the application from the second application head may be an application in a state where the reinforcing fiber sheet is not substantially horizontal, or may be a state in which the reinforcing fiber sheet is substantially horizontal but the resin discharge direction and the reinforcing fiber The case where the angle formed by the sheet conveying direction exceeds 80 °, and the case where the step of applying by contacting a die after the application step by the first application head, which is the application in the embodiment of the present invention, is combined. Can be

Next, some specific embodiments will be described with reference to FIG. For example, carbon fibers (T800S-24K manufactured by Toray Industries, Inc.) can be used as the reinforcing fibers 1 and 56 yarns can be used. The reinforcing fibers 1 are aligned in one direction by using the arrangement device 12 to form a reinforcing fiber sheet 1a having a width of 300 mm. The release paper 3a is inserted into the lower surface of the reinforcing fiber sheet 1a by the transport roll 13a. Then, the resin 2a is applied to the reinforcing fiber sheet 1a from the first application head 20a. At this time, as the resin 2a, a resin A composed of a thermosetting epoxy resin (a mixture of an aromatic amine type epoxy resin and a bisphenol type epoxy resin) containing a curing agent (diaminodiphenyl sulfone) and polyether sulfone may be used. it can. The viscosity of this resin A at 90 ° C. and 3.14 sec ⁻¹ can be 15 Pa · s.

  As the coating head 20a, a die coater having a slit die having a thickness of 0.4 mm and a width of 300 mm in the width direction can be used. The resin can be melted in a melter and then metered by a gear pump and supplied to the application section. In addition, a melter-a supply part-a die coater are heated so that it may become the same temperature. The surface air can be supplied from a slit having a thickness of 0.1 mm right next to the application section. The end air can be supplied via a copper tube of φ2 mm. The application height H can be set to 10 mm, and the application angle can be set to 65 °. The end portion air pressure can be 0.1 MPa and the surface air pressure can be 0.2 MPa. The resin 2 is collected on the table 18a, and the reinforcing fiber sheet 1a can be transported in a straight line even if there is air at the end and air at the surface.

<Aspect A>
As a first embodiment, embodiment A will be described below. First, the prepreg 1b can be formed by discharging the resin A from the first application head 20a in a planar shape. Here, the coating angle of the first coating head 20a can be 65 °, the temperature can be 90 ° C., and the discharge amount of the resin A can be 360 g / min. After that, the second coating head 20b is not used, the release paper 3b is inserted into the upper surface of the prepreg 1b to which the resin is applied by the transport roll 13b, and impregnation is performed by the first impregnation machine 17a, and the first cooling is performed. It can be cooled in the device 19a. Then, the release paper 3b is peeled off by the transport roll 13c, and the resin 2c can be applied onto the prepreg 1d using the third application head 20c. At this time, the resin 2c is composed of a thermosetting epoxy resin (a mixture of an aromatic amine type epoxy resin and a bisphenol type epoxy resin) containing a curing agent (diaminodiphenyl sulfone), polyether sulfone, and fine particles made of a thermoplastic resin. Resin B can be used. Here, as the thermoplastic resin fine particles, “particle 3” described in Examples of JP-A-2011-162609 can be used. The viscosity of the resin B at 105 ° C. and 3.14 sec ⁻¹ can be 15 Pa · s. The application angle of the third application head 20b can be 65 °, the temperature can be 105 ° C., and the discharge amount of the resin B can be 240 g / min. Thereafter, the release paper 3c is inserted into the upper surface of the prepreg 1e by the transport roll 13d, impregnated by the second impregnating machine 17b, cooled by the second cooling device 19b, and can be wound by the winding device 16. . In addition, the transport speed of the prepreg can be set to 20 m / min. In this manner, a prepreg containing organic fine particles can be manufactured.

<Aspect B>
In an embodiment B which is another embodiment different from the embodiment A, a resin C composed of a mixture of an aromatic amine type epoxy resin and polyether sulfone is used as the resin 2a to be applied by the first coating head 20a, and the discharge rate is 280 g / min. The temperature of the coating head 20a can be 120 ° C., and the coating angle can be 65 °. The viscosity of the resin C at 120 ° C. and 3.14 sec ⁻¹ can be 7 Pa · s. At this time, since the viscosity of the resin C is low, the coating height can be reduced to 5 mm. Further, as the resin 2b to be applied by the second application head 20b, a resin D made of a bisphenol-type epoxy resin containing a curing agent (diaminodiphenylsulfone) is used, the ejection rate is 320 g / min, the temperature of the application head 20b is 30 ° C. The application angle can be 65 °. The viscosity of the resin D at 30 ° C. and 3.14 sec ⁻¹ can be 15 Pa · s. Polyethersulfone requires a high temperature for application because the molecular chains become long and viscous due to long entanglement.On the other hand, the curing agent is preferably handled at a low temperature to suppress the curing reaction. . For this reason, if a high viscosity substance such as polyether sulfone is separated from the curing agent as in the present embodiment B, it is possible to set a preferable temperature for each application head. Each resin is applied to the carbon fiber sheet to form a prepreg 1d to which the resin is applied, and after the release paper 3b is inserted into the upper surface, impregnation is performed by the first impregnating machine 17a and cooling is performed by the first cooling device 19a. It can be carried out. Thereafter, the release paper 3b can be peeled off and taken up by the take-up device 16. In general, if there are many resins having a high storage modulus on the prepreg surface, the sticking property (tack property) is reduced. In a matrix resin for CFRP, a thermoplastic resin such as polyethersulfone has a higher storage elastic modulus than an epoxy resin. The prepreg obtained in the above mode B can reduce the amount of polyether sulfone present on the surface of the prepreg, so that the tackiness can be enhanced.

  In the above aspect B, a bisphenol-type epoxy resin containing thermoplastic resin fine particles (the “particle 3”) is used as the resin 2c in the third coating head, and the thermoplastic resin fine particles are further provided on the prepreg surface. (Aspect C). In addition, urethane particles or polyamide particles can be used instead of the “particle 3” (aspect D). A mixture of a bisphenol-type epoxy resin and carbon particles may be provided instead of the thermoplastic resin fine particles (Embodiment E). Further, inorganic particles such as metal particles and metal oxides / nitrides can be used instead of carbon particles (aspect F). Further, instead of the fine particles, a mixture of a flame retardant such as red phosphorus and an epoxy resin can be used (aspect G).

  Further, after the prepreg is formed by the production method of the present invention, solid matter such as particles can be spread on the prepreg until the winding step. The solid material can be selected according to the purpose, such as a curing agent, organic fine particles for improving toughness and vibration damping properties, inorganic fine particles for improving conductivity, and a flame retardant.

  It is also preferable that, after forming the prepreg by the manufacturing method of the present invention, subsequently, slitting is performed, and the prepreg is taped and wound. At this time, it is preferable to sufficiently advance the impregnation of the resin on the prepreg or sufficiently cool the prepreg in consideration of the processability in the slitting process and the suppression of the adhesion of dirt to the cutter.

  In the above description, the production of a prepreg having a width of 300 mm using 56 carbon fibers has been described. However, it is preferable to use an apparatus having a width of 1000 mm or 1600 mm or a wider width from the viewpoint of production efficiency. Naturally, the number of yarns and fineness of the carbon fibers to be used can be appropriately selected accordingly.

  The prepreg obtained by the production method of the present invention can be converted to CFRP by ordinary CFRP conversion technology and equipment. After obtaining the prepreg by the above-described prepreg production method, curing the prepreg to produce a fiber-reinforced composite material. Therefore, versatility and equipment compatibility are high. Therefore, it can be suitably used for articles made of various CFRPs and / or contained in a part thereof.

(Reinforced fiber sheet)
An UD sheet having a width of 280 mm was formed using 56 yarns of carbon fiber "Treca (registered trademark)" T800S-24K (manufactured by Toray Industries, Inc.) using the arrangement device 12 in FIG.

(Matrix resin)
In each of Examples and Comparative Examples, a resin E having the following composition was used as a matrix resin of the prepreg. The resin E is composed of an epoxy resin (a mixture of an aromatic amine type epoxy resin and a bisphenol type epoxy resin) containing a curing agent (diaminodiphenyl sulfone) and polyether sulfone.

(Viscosity measurement)
The viscosity of the matrix resin was measured using a dynamic viscoelasticity measuring device (ARES: manufactured by TA Instruments). In this apparatus, a parallel plate having a diameter of 40 mm is used, a gap between the plates is set to 1 mm, and a matrix resin is set therebetween. Then, the measurement was carried out at a measurement frequency of 0.5 Hz (3.14 sec ^-1 ) and a heating rate of 1.5 ° C./min to obtain a temperature-viscosity curve. The viscosity of the resin E was 35 Pa · s at 70 ° C. The viscosities of the matrix resins shown in the examples and comparative examples are obtained by reading the viscosities at the set temperature of the application section in the temperature-viscosity curves obtained here.

(Resin coating device)
As a coating device, a die coater having a thickness of 0.4 mm and a slit die of 300 mm in the width direction was used. The resin was melted by a melter, then measured by a gear pump, and supplied to a coating section. The melter, the supply unit, and the die coater were heated to the same temperature. The surface air 21 was supplied from a slit having a thickness of 0.1 mm right next to the application portion. The end air 22 was supplied via a copper tube having a diameter of 2 mm (see FIG. 9).

(Observation of reinforced fiber arrangement on prepreg surface)
The obtained prepreg was drawn out at least 1 m or more in the longitudinal direction and at least 1 m ² or more in total in the area of the prepreg, and a roughly minimum amount of sample satisfying both conditions was sampled, and the surface was visually observed. When there was no disorder in the fiber arrangement, it was evaluated as ○, and when part of the arrangement disorder was observed, it was evaluated as ×. For example, in the case of a prepreg having a width of 280 mm, the prepreg was pulled out at least 4 m in the longitudinal direction, sampled, and surface observation was performed visually.

(Evaluation of production speed)
The maximum production speed (running speed) that can be produced without breaking the resin film was evaluated, and a test of △ or more was judged as acceptable.
◎: 20 m / min or more ：: 10 m / min or more and less than 20 m / min △: 5 m / min or more and less than 10 m / min X: less than 5 m / min.

(Evaluation of stability)
The prepreg production stability was evaluated based on the continuous running time at a conveying speed (running speed) of 10 m / min.
：: 60 minutes or more Δ: 10 minutes or more and less than 60 minutes X: less than 10 minutes.

(Evaluation of neck-in)
The amount of each neck-in when the resin was applied onto the reinforcing fiber sheet (the length of the G portion; see FIGS. 5 and 6) was evaluated.
：: less than 10 mm △: 10 mm or more and less than 20 mm X: 20 mm or more.

  Hereinafter, each Example and Comparative Example will be described in detail.

[Examples 1 to 3]
The process used in this example is shown in FIG. 1 (the impregnating machine 17 was not used), and the coating apparatus is shown in FIG. The discharge rate of the resin E was 97 g / min, the temperature of the application section was 70 ° C., the air pressure at the end was 0.1 MPa, and the air pressure at the surface was 0.2 MPa. As a result, the resin E was applied to the carbon fiber sheet at the running speed of 20 m / min under the conditions shown in Table 1, but no fuzz clogging or yarn breakage occurred, no sign of fuzz clogging was observed, and an excellent prepreg was obtained. Production speed. Further, the carbon fiber sheet was coated with resin E, and no coating defects were observed. However, in Example 1 in which the coating angle θ was large, the stability was slightly unstable, though not so much as to cause a problem.

[Example 4]
The coating was performed in the same manner as in Example 1 except that the coating angle and the coating height were changed as shown in Table 1. In Example 4, since the application angle was as small as 25 °, there was a possibility that the application portion might interfere with the process. Therefore, the application height was set to 20 mm. As a result, the formation of the resin film in the air became slightly unstable, and the stability was slightly lowered, though not to a problem.

[Comparative Example 1]
Coating was performed in the same manner as in Example 1 except that the coating angle was 90 °, but at a running speed of 20 m / min, stable coating could not be performed due to breakage of the resin film. For this reason, in order to reduce the viscosity of the resin E, the temperature of the application section was increased to 105 ° C., and the running speed was further reduced, and a coating experiment was performed. However, both the production speed and the stability were poor. could not.

[Example 5]
Coating was carried out in the same manner as in Example 2 except that the running speed was 10 m / min, but neck-in was suppressed.

[Example 6]
The coating was performed in the same manner as in Example 5 except that the end air was not used, but the tendency of the neck-in to increase was observed.

[Examples 7 to 12]
A prepreg was produced under the same conditions as in Examples 1 to 6 except that the impregnation was performed using the impregnating machine 17 (Example 1 corresponds to Example 7, Example 2 corresponds to Example 8, and the same applies hereinafter). ). Furthermore, after laminating and bagging this in a pseudo-isotropic manner, it was cured in an autoclave at a temperature of 180 ° C. and a pressure of 6 atm for 2 hours to obtain a carbon fiber reinforced composite material. Good quality and mechanical properties were obtained.

[Examples 13 to 16]
Using 53 threads of carbon fiber and the following resin F as a matrix resin, the discharge rate of the resin F was 600 g / min, and the temperature of the application section was 85 ° C., and the prepreg was prepared in the same manner as in Examples 1 to 4 under the conditions shown in Table 3. Was prepared. Resin F is composed of an epoxy resin (mixture of aromatic amine type epoxy resin and bisphenol type epoxy resin) containing a curing agent (diaminodiphenyl sulfone) and polyether sulfone, and has a viscosity of 21 Pa at 85 ° C. and 3.14 sec ^−1. -It was s.

  In any of the examples, at a running speed of 10 m / min or more, there was no breakage of the resin film in the coating process, no disturbance in the fiber arrangement and no fuzzing caused by the coating were observed, and a prepreg of excellent quality was obtained. . In Examples 14 to 16, the running speed was as high as 20 m / min or more. Further, in Examples 14 and 15, the production stability was excellent. In Examples 13 to 15, neck-in was sufficiently suppressed.

[Comparative Example 2]
Coating was performed in the same manner as in Example 14 except that the coating angle was 90 °, but at a running speed of 20 m / min, stable coating could not be performed due to breakage of the resin film. For this reason, in order to reduce the viscosity of the resin E, the temperature of the application section was increased to 105 ° C., and the running speed was further reduced, and a coating experiment was performed. However, both the production speed and the stability were poor. could not.

[Example 17]
Coating was carried out in the same manner as in Example 14 except that the end air pressure was changed to 0.02 MPa. As a result, the neck-in tended to increase, although not to a problem.

[Example 18]
Coating was performed in the same manner as in Example 14 except that the running speed was 10 m / min and the surface air pressure was 0.02 MPa, but the running stability was not as good as that of Example 14 although it was not a problem. .

[Examples 19 to 24]
In Examples 19 and 24, the discharge rate of the resin F was 300 g / min and the production speed was 10 m / min. In Examples 20 to 23, the discharge amount of the resin F was 600 g / min and the production speed was 20 m / min. Prepregs were produced under the same conditions as in Examples 13 to 18 except that impregnation was performed using the impregnating machine 17 in all Examples (Example 13 corresponds to Example 19, and Example 14 corresponds to Example 20). Corresponding, the same applies hereinafter). Furthermore, after laminating and bagging this in a pseudo-isotropic manner, it was cured in an autoclave at a temperature of 180 ° C. and a pressure of 6 atm for 2 hours to obtain a carbon fiber reinforced composite material. Good quality and mechanical properties were obtained.

This application is based on Japanese Patent Application No. 2017-055613 filed on Mar. 22, 2017, the contents of which are incorporated herein by reference.

1 Reinforcing fiber 1a Reinforcing fiber sheet 1b, 1c, 1d, 1e Reinforcing fiber sheet (prepreg) provided with resin
2, 2a, 2b, 2c, 2d Resin 3, 3a, 3b, 3c Release sheet 11 Creel 12 Arrangement devices 13a, 13b, 13c, 13d, 13e Transport rolls 14a, 14b, 14c Release sheet supply devices 15, 15a 15b Release sheet take-up device 16 Take-up device 17 Impregnation device 18a, 18b, 18c Table 19, 19a, 19b Cooling device 20 Coating section 20a First coating head 20b Second coating head 20c Third coating head 21 Surface section Air 22 End air E End air blowing direction F Surface air blowing direction G Neck-in H Application height X Running direction of the reinforcing fiber sheet 1a (horizontal direction)
B Vertical direction θ with respect to the running direction (horizontal direction) of the reinforcing fiber sheet 1a

Claims (6)

  In a method for producing a prepreg in which a molten resin is discharged in a planar shape and the formed resin film is applied onto a continuously conveyed reinforcing fiber sheet, the reinforcing fiber sheet is conveyed substantially horizontally, A method for producing a prepreg, wherein the angle between the discharge direction of the prepreg and the conveying direction of the reinforcing fiber sheet is 80 ° or less.   2. The method for producing a prepreg according to claim 1, wherein, when applying the resin film on the reinforcing fiber sheet, an airflow acts on an end portion in a width direction of the resin film. The method for producing a prepreg according to claim 1 or 2, wherein a substance selected from the group consisting of a resin, a mixture of a resin and an additive, and an additive is applied to both surfaces of the reinforcing fiber sheet using two or more application heads.   The method for producing a prepreg according to any one of claims 1 to 3, wherein two or more application heads are used to apply two or more kinds of resins.   The method for producing a prepreg according to any one of claims 1 to 4, wherein impregnation is performed after applying the resin film on the reinforcing fiber sheet. A method for producing a fiber-reinforced composite material, comprising a step of curing the prepreg after obtaining the prepreg by the method for producing a prepreg according to claim 1.